Semiconductor device and method of manufacturing the same, circuit board, and electronic instrument

ABSTRACT

A substrate includes an insulating film in which a penetrating hole is formed, the penetrating hole extending between a first surface of the insulating film and a second surface of the insulating film opposite to the first surface of the insulating film. A wiring pattern is adhered to the first surface of the insulating film by an adhesive material. A first portion of the wiring pattern is formed over the penetrating hole, and a part of the adhesive material is formed on an internal wall surface forming the penetrating hole so as not to stop up the penetrating hole. An external electrode contacts the first portion of the wiring pattern and projects through the penetrating hole and extends beyond the second surface of the insulating film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and method ofmanufacture thereof, a circuit board, and an electronic instrument.

2. Description of Related Art

With the recent increasingly compact nature of electronic instruments,there is a demand for semiconductor device packages appropriate forhigh-density mounting. In response to this, surface-mounted packageshave been developed, such as Ball Grid Array (BGA) and Chip Scale/SizePackage (CSP). With such surface-mounted packages, a substrate is oftenused on which a wiring pattern for connection to the semiconductor chipis formed. Penetrating holes are formed in the substrate, and externalelectrodes are often formed so as to project through these penetratingholes from the surface opposite to that of the wiring pattern.

With a semiconductor device to which a package of this construction isapplied, after mounting on the circuit board, because of the differencein coefficient of thermal expansion between the circuit board andsemiconductor device, a stress may be applied to the externalelectrodes, and cracks may form in the external electrodes.

SUMMARY OF THE INVENTION

The present invention solves these problems, and has as its object theprovision of a semiconductor device and method of manufacture thereof, acircuit board, and an electronic instrument such that cracks in theexternal electrodes can be prevented.

(1) According to a first aspect of the present invention, there isprovided a semiconductor device comprising:

a substrate in which penetrating holes are formed;

a semiconductor chip having electrodes;

a conductive member adhered on one side of the substrate by an adhesivematerial over a particular region of the one side including thepenetrating holes, and electrically connected to the electrodes of thesemiconductor chip on the side opposite to the surface of being adheredby the adhesive; and

external electrodes which are provided through the penetrating holes,electrically connected to the conductive member, and extending as far asoutside of the other side of the substrate;

wherein a part of the adhesive material is interposed between internalwall surfaces forming the penetrating holes and the external electrodeswithin the penetrating holes.

According to the present invention, external electrodes are formedwithin penetrating holes, and between the external electrodes andpenetrating holes part of an adhesive material is interposed. Therefore,since the adhesive material forms a stress absorption material, stresscaused by differences in the coefficient of thermal expansion with thecircuit board (thermal stress) and mechanical stress applied to thecircuit board from the outside can be absorbed. In this way, theoccurrence of cracks in the external electrodes can be prevented.

It should be noted that in the present invention, the adhesive materialmay be continuous from between the substrate and conductive member tothe internal wall surfaces of the penetrating holes, or may existdiscontinuously within the penetrating holes.

(2) In this semiconductor device, a part of the adhesive material mayenter and exist within the penetrating holes.

(3) According to a second aspect of the present invention, there isprovided a semiconductor device comprising:

a substrate in which penetrating holes are formed;

a semiconductor chip having electrodes;

a conductive member directly formed over a particular region includingthe penetrating holes on one side of the substrate, and electricallyconnected to the electrodes of the semiconductor chip; and

external electrodes which are provided through the penetrating holes,electrically connected to the conductive member, and extending as far asoutside of the other side of the substrate;

wherein the substrate is formed of a material of a higher elasticitythan the external electrodes; and

wherein protrusions are formed in the internal wall surfaces of thepenetrating holes by the material constituting the substrate.

According to the present invention, since protrusions are formed in theinternal wall surfaces of the penetrating holes, deformation is easierthan with flat internal wall surfaces. Therefore, stress caused bydifferences in the coefficient of thermal expansion with the circuitboard (thermal stress) and mechanical stress applied to the circuitboard from the outside can be absorbed. In this way, the occurrence ofcracks in the external electrodes can be prevented.

(4) Each of the external electrodes may include a base portionpositioned within each of the penetrating holes and a projecting portionprojecting from each of the penetrating holes, the diameter d of thebase portion being related to the diameter φ of the projecting portionby φ≦d.

By this means, the diameter of the external electrode is not squeezed bythe penetrating hole, and no necking occurs. Therefore, stress caused bydifferences in the coefficient of thermal expansion with the circuitboard (thermal stress) and mechanical stress applied from outside thecircuit board is not concentrated, and the occurrence of cracks in theexternal electrodes can be prevented.

(5) According to a third aspect of the present invention, there isprovided a semiconductor device comprising:

a substrate in which penetrating holes are formed;

a semiconductor chip having electrodes;

a conductive member adhered on one side of the substrate by an adhesivematerial over a particular region of the one side including thepenetrating holes, and electrically connected to the electrodes of thesemiconductor chip on the side opposite to the surface of being adheredby the adhesive; and

external electrodes which are provided through the penetrating holes,electrically connected to the conductive member, and extending as far asoutside of the other side of the substrate;

wherein each of the external electrodes includes a base portionpositioned within each of the penetrating holes and a projecting portionprojecting from each of the penetrating holes, the diameter d of thebase portion being related to the diameter φ of the projecting portionby φ≦d.

According to the present invention, external electrodes are formedwithin penetrating holes. The diameter d of the base portion of theexternal electrodes is related to the diameter φ of the projectingportion by φ≦d. In other words, the diameter of the external electrodesis not squeezed by the penetrating holes, and no necking occurs.Therefore, stress caused by differences in the coefficient of thermalexpansion with the circuit board (thermal stress) and mechanical stressapplied from outside the circuit board is not concentrated, and theoccurrence of cracks in the external electrodes can be prevented.

(6) The substrate may be an insulating substrate.

(7) The substrate may be a printed substrate.

(8) The external electrodes may be formed of solder.

(9) The outline form of the substrate may be larger than thesemiconductor chip outline form.

(10) The electrodes of the semiconductor chip may be electricallyconnected to the conductive member through an anisotropic conductivematerial having conductive particles dispersed in an adhesive.

(11) The electrodes of the semiconductor chip may be electricallyconnected to the conductive member through wires.

(12) According to a fourth aspect of the present invention, there isprovided a circuit board on which the above described semiconductordevice is mounted.

(13) According to a fifth aspect of the present invention, there isprovided an electronic instrument having the above described circuitboard.

(14) According to a sixth aspect of the present invention, there isprovided a method of manufacturing a semiconductor device, comprising:

a step of providing a substrate with an adhesive material provided onone surface thereof;

a step of carrying out punching from the side of the substrate on whichthe adhesive material is provided, and in the direction of the oppositeside thereof, whereby penetrating holes are formed and a part of theadhesive material is drawn into the penetrating holes;

a step of adhering a conductive member over a particular region on theone surface including the penetrating holes on the substrate through theadhesive material;

a step of providing a material for forming external electrodes on theconductive member, and forming external electrodes through thepenetrating holes and the inner side of the part of adhesive materialdrawn into the penetrating holes to project from the surface opposite tothe surface of the substrate on which the conductive member is formed;and

a step of electrically connecting electrodes of a semiconductor chip tothe conductive member.

According to the present invention, when the substrate is punched andthe Penetrating holes are formed, at the same time part of the adhesivematerial can be drawn into the penetrating holes. When the externalelectrodes are formed through the penetrating holes, this part of theadhesive material is interposed between the external electrodes andpenetrating holes. With the thus obtained semiconductor device, theadhesive material acts as a stress absorption material, and thereforestress caused by differences in the coefficient of thermal expansionwith the circuit board (thermal stress) and mechanical stress appliedfrom outside the circuit board is absorbed, and the occurrence of cracksin the external electrodes can be prevented.

(15) According to a seventh aspect of the present invention, there isprovided a method of manufacturing a semiconductor device, comprising:

a step of providing a substrate of a material of a higher elasticitythan external electrodes, having penetrating holes in which the internalwall surfaces have protrusions, and having a conductive member directlyformed over a region including the penetrating holes;

a step of providing a material for forming external electrodes on theconductive member, and forming external electrodes through thepenetrating holes to project from the surface opposite to the surface ofthe substrate on which the conductive member is formed; and

a step of electrically connecting electrodes of semiconductor chip tothe conductive member.

According to the present invention, since protrusions are formed in theinternal wall surfaces of the penetrating holes, deformation is easierthan with flat internal wall surfaces. Therefore stress caused bydifferences in the coefficient of thermal expansion with the circuitboard (thermal stress) and mechanical stress applied to the circuitboard from the outside can be absorbed. In this way, the occurrence ofcracks in the external electrodes can be prevented.

(16) The method of manufacturing the semiconductor device may furthercomprise a step of punching the substrate before the conductive memberis formed, wherein a part of the substrate is drawn into the penetratingholes and the protrusions are formed.

By this means, in the step of punching, the protrusions can be formedsimply.

(17) In this method of manufacture, the penetrating holes may be formedby a laser.

When a laser is used, the protrusions occur naturally.

(18) In this method of manufacture, the penetrating holes may be formedby wet etching.

When wet etching is applied, the protrusions occur naturally.

(19) In this method of manufacture, wherein each of the externalelectrodes includes a base portion positioned within each of thepenetrating holes and a projecting portion projecting from each of thepenetrating holes, the diameter d of the base portion being related tothe diameter φ of the projecting portion by φ≦d.

By this means, the diameter of the external electrodes is not squeezedby the penetrating holes, and no necking occurs. Therefore, stresscaused by differences in the coefficient of thermal expansion with thecircuit board (thermal stress) and mechanical stress applied fromoutside the circuit board is not concentrated, and the occurrence ofcracks in the external electrodes can be prevented.

(20) According to an eighth aspect of the present invention, there isprovided a method of manufacturing a semiconductor device, comprising:

a step of providing a substrate in which penetrating holes are formedand a conductive member is formed over a region including thepenetrating holes;

a step of providing a material for forming external electrodes on theconductive member, and forming external electrodes through thepenetrating holes to project from the surface opposite to the surface ofthe substrate on which the conductive member is formed; and

a step of electrically connecting electrodes of a semiconductor chip tothe conductive member;

wherein each of the external electrodes includes a base portionpositioned within each of the penetrating holes and a projecting portionprojecting from each of the penetrating holes, the diameter d of thebase portion being related to the diameter φ of the projecting portionby φ≦d.

With a semiconductor device fabricated according to the presentinvention, the diameter d of the base portion of the external electrodesis related to the diameter φ of the projecting portion by φ≦d. In otherwords, the diameter of the external electrodes is not squeezed by thepenetrating holes, and no necking occurs. Therefore, stress caused bydifferences in the coefficient of thermal expansion with the circuitboard (thermal stress) and mechanical stress applied from outside thecircuit board is not concentrated, and as a result the occurrence ofcracks in the external electrodes can be prevented.

(21) The substrate may be either of an insulating film and a printedsubstrate.

(22) The material for forming external electrodes may be solder.

(23) The method of manufacturing a semiconductor device may furthercomprise a step of punching the substrate around the semiconductor chip,after the step of electrically connecting electrodes of thesemiconductor chip to the conductive member.

(24) In the step of electrically connecting the electrodes of thesemiconductor chip to the conductive member, the electrodes may beconnected to the conductive member through an anisotropic conductivematerial having conductive particles dispersed in an adhesive.

(25) In the step of electrically connecting the electrodes of thesemiconductor chip to the conductive member, the electrodes may beconnected to the conductive member through wires.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of thesemiconductor device.

FIGS. 2A and 2B show the method of manufacturing the first embodiment ofthe semiconductor device.

FIG. 3 shows a modification of the first embodiment of the semiconductordevice.

FIG. 4 is a cross-sectional view of a second embodiment of thesemiconductor device.

FIG. 5 shows a third embodiment of the semiconductor device.

FIG. 6 shows a fourth embodiment of the semiconductor device.

FIG. 7 is a cross-sectional view of a fifth embodiment of thesemiconductor device.

FIGS. 8A and 8B show the method of manufacturing the fifth embodiment ofthe semiconductor device.

FIG. 9 shows the method of manufacturing the fifth embodiment of thesemiconductor device.

FIG. 10 shows the method of manufacturing the fifth embodiment of thesemiconductor device.

FIG. 11 shows a circuit board on which is mounted the present embodimentof a semiconductor device.

FIG. 12 shows an electronic instrument provided with a circuit board onwhich is mounted the present embodiment of a semiconductor device.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is now described in terms of a number of preferredembodiments, with reference to the drawings.

First Embodiment

FIG. 1 shows a first embodiment of the semiconductor device. Asemiconductor device 10 comprises a semiconductor chip 12, being anexample of a semiconductor chip, and an insulating film 14, being anexample of a substrate, to which the CSP type of package is applied. Onthe insulating film 14 are formed external electrodes 16, and thesemiconductor chip 12 has a plurality of electrodes 13. In FIG. 1, theelectrodes 13 are formed on only two opposite sides of the semiconductorchip 12, but as is well known, may equally be formed on four sides.

The insulating film 14 is formed of a polyimide resin or the like, andhas a plurality of penetrating holes 14 a. As the substrate formed ofpolyimide resin may be used one such that for example:

Coefficient of thermal expansion=12 ppm/° C.

Modulus of elasticity=900 kg/mm²

Or one such that:

Coefficient of thermal expansion=20 ppm/° C.

Modulus of elasticity=302 kg/mm²

To one surface of the insulating film 14 is adhered a wiring pattern 18,being an example of a conductive element. In more detail, the wiringpattern 18 is adhered to the insulating film 14 by an adhesive 17. Asthe adhesive 17, being an example of an adhesive material may be usedone such that:

Coefficient of thermal expansion (50 to 150° C.)=70 to 165 ppm/° C.

Modulus of elasticity (150° C.)=0.1 to 0.9×10⁸ Pa

Elongation after fracture=13 to 29%

And may be used one such that for example:

Coefficient of thermal expansion (50 to 150° C.)=70 ppm/° C.

Modulus of elasticity (150° C.)=0.1×10⁸ Pa

Elongation after fracture=21%

A part of the adhesive 17 enters the penetrating holes 14 a. It shouldbe noted that in place of the adhesive 17 may be used an adhesive tapeor the like. The wiring pattern 18 is formed so as to pass over thepenetrating holes 14 a, and although not shown in FIG. 1, the portionsincluding the position over the penetrating holes 14 a are lands ofgreater width than other portions.

Further, in the insulating film 14 external electrodes 16 are formed,through the penetrating holes 14 a, on the wiring pattern 18 (below inthe figure). The external electrodes 16 include base portions 16 abonded to the wiring pattern 18 at positions within the penetratingholes 14 a, and projecting portions 16 b projecting from the insulatingfilm 14 on the opposite side to the wiring pattern 18. It should benoted that external electrodes 16 are formed of solder, copper, nickel,or the like.

In this embodiment, as shown in enlargement in FIG. 1, a part of theadhesive 17 is interposed between the base portions 16 a of the externalelectrodes 16 and the penetrating holes 14 a. By means of this part ofthe adhesive 17, stress (thermal stress or mechanical stress) applied tothe external electrodes 16 is absorbed. The stress often occurs whenheat is applied, and therefore the adhesive 17 is required to have adegree of flexibility and elasticity at least when heat is applied suchas to function to absorb the stress.

On each part of the wiring pattern 18 is formed a projection 18 a. Theprojections 18 a are formed to correspond to the electrodes 13 of thesemiconductor chip 12. As a result, if the electrodes 13 are arranged onthe four sides of the periphery of the semiconductor chip 12, theprojections lea will also be arranged along the four sides. Theelectrodes 13 are electrically connected to the projections 18 a, andthrough the wiring pattern 18 are conductively connected to the externalelectrodes 16. By the formation of the projections 18 a, a wide gap canbe formed between the insulating film 14 and the semiconductor chip 12or between the wiring pattern 18 and the semiconductor chip 12.

The electrical connection of the electrode 13 and projection 18 a isachieved by means of an anisotropic conductive film 20 being an exampleof an anisotropic conductive material. The anisotropic conductive film20 comprises conductive particles such as metal fine particles dispersedin a resin in sheet form. When the anisotropic conductive film 20 iscompressed between the electrodes 13 and projections lea, the conductiveparticles are also compressed, forming electrical connection between thetwo. When the anisotropic conductive film 20 is used, the conductiveparticles conduct electricity only in the direction in which they arecompressed, and do not conduct electricity in other directions. As aresult, even when the sheet-form anisotropic conductive film 20 isadhered on the plurality of electrodes 13, there is no electricalconnection between adjacent of the electrodes 13.

In the above described example, the projections 18 a are formed on thewiring pattern 18, but equally, bumps may be formed on the electrodes 13of the semiconductor chip 12, and in this case, the projections 18 a donot need to be formed on the wiring pattern 18.

In this embodiment, the anisotropic conductive film 20 is formed onlybetween the electrodes 13 and projections 18 a and in the vicinitythereof, but it may equally be formed only between the electrodes 13 andprojections 18 a, or may be formed over the whole surface of thesemiconductor chip 12, including the region in which a resin 22described below is injected.

In the gap formed between the insulating film 14 and the semiconductorchip 12, a resin 22 is injected from a gel injection aperture 24. Itshould be noted that when the anisotropic conductive film 20 is formedover the whole surface of the semiconductor chip 12 the injectionaperture 24 is not necessary, and moreover the step of injecting theresin 22 is not required.

If as the resin 22 is used a material with a low Young's modulus and anability to absorb stress, then in addition to the stress absorptionfunction of the adhesive 17, further stress absorption can be achieved.For example, by using polyimide resin, silicone resin, siliconedenatured polyimide resin, epoxy resin, silicone denatured epoxy resin,acrylic resin, and so forth, the resin 22 provides a stress absorptionfunction.

Next, the principal steps in the method of manufacturing the presentembodiment of the semiconductor device 10 are described.

First, the insulating film 14 with the adhesive 17 provided on onesurface is taken, and penetrating holes 14 a are formed in theinsulating film 14. This step is shown in FIGS. 2A and 2B. Morespecifically, as shown in FIG. 2A, first, a punch 1 and a die 2 aredisposed on the side on which the adhesive 17. In this figure, theinsulating film 14 is positioned with the surface having the adhesive 17uppermost, and the punch 1 is positioned above. It should be noted thatthe insulating film 14 is mounted on a support not shown in the figure.Then as shown in FIG. 2B, the insulating film 14 is penetrated by thepunch 1, and penetrating holes 14 a are formed. The punch 1 is guided bythe die 2, and drags in the adhesive 17 as it penetrates the insulatingfilm 14. As a result, part of the adhesive 17 is drawn into the interiorof the penetrating holes 14 a. The adhesive 17 drawn into thepenetrating holes 14 a does not return when the punch 1 is withdrawn,but remains within the penetrating holes 14 a. It should be noted thatin order for the adhesive 17 to be drawn into the penetrating holes 14a, it is preferable for there to be a clearance of the order of 10 to 50μm between the punch 1 and die 2.

Preferably, at the same time that the penetrating holes 14 a are formed,a gel injection aperture 24 is also formed in the insulating film 14.

Then a conductive film such as a copper foil is adhered to theinsulating film 14, and by etching the wiring pattern 18 is formed. Bymasking the region of formation of the projections 18 a and etching sothat other portions are made thin, when the mask is removed, theprojections 18 a can be formed.

Next, the anisotropic conductive film 20 is adhered on the insulatingfilm 14 over the projections 18 a. In more detail, when the plurality ofprojections 18 a are arranged along two opposing sides, the anisotropicconductive film 20 is adhered in two parallel strips, and when theprojections 18 a are arranged along four sides, the anisotropicconductive film 20 is adhered so as to describe a correspondingrectangle.

In this way, the above described insulating film 14 is pressed onto thesemiconductor chip 12 such that the projections 18 a and electrodes 13correspond, and the anisotropic conductive film 20 is compressed by theprojections 18 a and electrodes 13. In this way, electrical connectionof the projections 18 a and electrodes 13 can be achieved.

Next, resin is injected from the gel injection aperture 24, and theresin 22 is formed between the insulating film 14 and the semiconductorchip 12.

Then through the penetrating holes 14 a, solder is disposed on thewiring pattern 18, and ball-shaped external electrodes 16 are formed.More specifically, for example, a solder paste is used to print thesolder, or solder balls are disposed on the wiring pattern 18 so thatthe external electrodes 16 are formed.

By means of these processes, the semiconductor device 10 can beobtained. It should be noted that in this embodiment, the anisotropicconductive film 20 is used, but in place of this an anisotropicconductive adhesive may be used. Except for the fact that theanisotropic conductive adhesive is not in sheet form, it has the sameconstruction as the anisotropic conductive film 20.

According to this embodiment, since the adhesive 17 is present betweenthe external electrodes 16 and penetrating holes 14 a formed in theinsulating film 14, stress (thermal stress or mechanical stress) appliedto the external electrodes 16 can be absorbed. In order to obtain such aconstruction, as described above, the adhesive 17 is provided beforehandon the insulating film 14, and a step is carried out of punching thepenetrating holes 14 a from the side of the adhesive 17. By this means,simultaneous with the punching of the penetrating holes 14 a, part ofthe adhesive 17 can be drawn into the penetrating holes 14 a.

FIG. 3 shows a modification of this embodiment. In this modification,the adhesive 17 does not enter the penetrating holes 14 a in theinsulating film 14, and the external electrodes 26 have a particularform. Since it is not necessary for the adhesive 17 to enter thepenetrating holes 14 a, a printed circuit board not having the adhesive17 can be used in place of the insulating film 14.

In this case, the diameter d of the base portion 26 a of the externalelectrode 26 and the diameter φ of the projecting portion 26 b are suchthat the relation

φ≦d

holds. In other words, the base portion 26 a positioned in the extremityof the openings of the penetrating holes 14 a is approximately equal tothe projecting portion 26 b projecting from the insulating film 14 onthe periphery of the penetrating hole 14 a, or alternatively the baseportion 26 a is larger than the projecting portion 26 b. In particular,it is preferable that the two are approximately equal. In this way,going from the projecting portion 26 b to the base portion 26 a a neckedform is prevented from being formed.

According to this construction, since the external electrodes 26 do nothave a necked form, stress applied to the external electrodes 26 is notconcentrated. Moreover, the stress is distributed, and cracks can beprevented. It should be noted that if the construction in which theadhesive 17 enters the penetrating holes 14 a is adopted, the stressabsorption capability is further enhanced.

The method of manufacture is the same as in the above describedembodiment. However, since a step of causing the adhesive 17 to enterthe penetrating holes 14 a is not necessarily required, the direction ofpunching the penetrating holes 14 a is not restricted. For example, byforming the wiring pattern 18 on the insulating film 14 by sputtering,the adhesive 17 may be omitted in this modification. However, it is notthe case that the adhesive 17 is prevented from being present betweenthe penetrating holes 14 a and the external electrodes 26.

Second Embodiment

FIG. 4 shows a second embodiment of the semiconductor device. Thissemiconductor device 110 includes a semiconductor chip 112, aninsulating film 14 being an example of a substrate (the sameconstruction as the first embodiment), and a plurality of externalelectrodes 16 (the same construction as the first embodiment). Bumps 113are provided on a plurality of electrodes (not shown in the drawing) ofthe semiconductor chip 112. The bumps 113 are commonly gold ball bumpsor gold plating bumps, but may equally be solder balls. The insulatingfilm 14 is formed to be larger than the semiconductor chip 112.

On one surface of the insulating film 14 is adhered a conductive member118. The conductive member 118 is formed as the wiring pattern 18 shownin FIG. 1 with the projections 18 a omitted, and is attached to theinsulating film 14 with an adhesive 17.

The electrical connection of the bumps 113 and conductive member 118 isachieved by an anisotropic conductive material 120 provided over thewhole surface of the side of the insulating film 14 on which is formedthe conductive member 118. As the anisotropic conductive material 120can be used the same material as the anisotropic conductive film 20shown in FIG. 1. By this means, the anisotropic conductive material 120is interposed between the semiconductor chip 112 and the insulating film14, and the surface of the semiconductor chip 112 on which electrodesare formed, and the surface of the insulating film 14 on which theconductive member 118 are formed are covered and protected. Otherconstruction is the same as in the first embodiment.

For the method of manufacturing the present embodiment of thesemiconductor device 110, the same method as described for the firstembodiment can be applied, except for the provision of the anisotropicconductive material 120 over the whole surface of the insulating film14. When fabricating the semiconductor device 110, the semiconductorchip 112 may be mounted on a substrate, and then this substrate stampedout in the form of the insulating film 14. In this embodiment also, forthe form of the external electrodes 16, the form shown in FIG. 3 can beapplied.

Third Embodiment

FIG. 5 shows a third embodiment of the semiconductor device of thepresent invention. The semiconductor device 30 shown in this figure hasa wiring pattern 38 and electrodes 33 of a semiconductor chip 32connected by wires 40. The wiring pattern 38 is formed by adhesion to asubstrate 34 with an adhesive 37 interposed. The substrate 34 may be aninsulating film in the same way as in the first embodiment, or a printedcircuit board.

On the surface of the substrate 34 on which the wiring pattern 38 isformed, a stress relieving layer 42 is provided. The stress relievinglayer 42 is formed of a material such as may be selected as the resin 22in the first embodiment. The stress relieving layer 42 is affixed bymeans of an adhesive 46 to the surface opposite to the surface havingthe electrodes 33 of the semiconductor chip 32.

In the substrate 34 are formed penetrating holes 34 a. Through thesepenetrating holes 34 a, external electrodes 36 are formed on the wiringpattern 38. In more detail, the external electrodes 36 are formed on thewiring pattern 38 so as to project from the opposite surface of thesubstrate 34 from the wiring pattern 38. Then the periphery of thesemiconductor chip 32 and the surface of the substrate 34 having thewiring pattern 38 are sealed with a resin 44.

The external electrodes 36 have the same construction as that shown inFIG. 1 or that of the external electrodes 26 shown in FIG. 3, and thesame effect can be achieved. Alternatively, in the same way as theembodiment shown in FIG. 1, the adhesive 37 may be interposed betweenthe penetrating holes 34 a and the external electrodes 36.

This embodiment differs from the first embodiment in that the wires 40are used to connect the electrodes 33 of the semiconductor chip 32 andthe wiring pattern 38, and in that the semiconductor chip 32 and soforth is sealed with the resin 44, but in relation to the stressabsorption function, is the same as the first embodiment.

Fourth Embodiment

FIG. 6 shows a fourth embodiment of the semiconductor device of thepresent invention. A semiconductor device 130 shown in this figurediffers from the semiconductor device 30 shown in FIG. 5 in that theadhesive 37 is present between the penetrating holes 34 a and externalelectrodes 136.

Fifth Embodiment

FIG. 7 shows a fifth embodiment of the semiconductor device of thepresent invention. A semiconductor device 210 shown in this figurediffers from the semiconductor device 110 shown in FIG. 4 in that theconductive member 118 is directly formed on a substrate 214 without anadhesive material. In FIG. 7, components same as in the semiconductordevice 110 shown in FIG. 4 have the same reference numerals. It shouldbe noted that in this embodiment, the semiconductor chip 112 issubjected to face-down mounting, but the face-up mounting shown in FIG.6 may equally be applied.

The substrate 214 is formed of a material with a higher elasticity thanthe external electrodes 16. On the internal walls of penetrating holes214 a of the substrate 214 are formed protrusions 220. The method offorming the protrusions 220 is shown in FIGS. 8A and 8B.

The substrate 214 differs from the insulating film 14 shown in FIG. 2 inthat no adhesive is provided. As shown in FIG. 8A, the substrate 214mounted on the die 2 has the penetrating holes 214 a formed by the punch1 as shown in FIG. 8B. By this means, the material constituting thesubstrate 214 is formed into protrusions 220 protruding within thepenetrating holes 214 a. For example, on one surface of the substrate214 a part of the portion forming the extremities of the penetratingholes 214 a may be drawn into the penetrating holes 214 a to form theprotrusions 220, or at an intermediate position in the thickness of thesubstrate 214 the protrusions 220 may be formed on the internal walls ofthe penetrating holes 214 a. The protrusions 220 may have the entireperiphery of the penetrating holes 214 a formed to be protruding in aring form within the penetrating holes 214 a, or may be constituted witha part only of the periphery of the penetrating holes 214 a protrudingwithin the penetrating holes 214 a. By the formation of the protrusions220, the same effect can be achieved as of the adhesive 17 being presentwithin the penetrating holes 14 a, as shown in FIG. 4. In other words,compared with the case in which the internal walls of the penetratingholes 214 a are flat, since the protrusions 220 are easily deformed,stress applied to the external electrodes 16 can be absorbed.

In this way, after the penetrating holes 214 a are formed, theconductive member 118 is formed on the substrate 214, to constitutetwo-layer substrate. For example, if the substrate 214 is of athermoplastic substance, it can be softened by heating, and a conductivefoil adhered without the use of adhesive, and by etching thereof aconductive member 218 can be formed. Alternatively, sputtering mayequally be applied.

Alternatively, as shown in FIG. 9, penetrating holes 330 may be formedin a substrate 300 on which a conductive member 310 is formed, using alaser 320. In this case also, in the penetrating holes 330 are formedprotrusions 332. If a CO₂ laser is used as the laser 320 the protrusions332 are easily formed, but an excimer laser may also be used.

As shown in FIG. 10, a resist layer 420 having openings 422corresponding to the penetrating holes may be formed on a substrate 400on which a conductive member 410 is formed, and by carrying out wetetching penetrating holes 430 may be formed. In this case also, sincethe internal walls of the penetrating holes 430 are uneven, protrusions432 are formed.

It should be noted that the above described embodiment is asemiconductor device to which CSP type packaging is applied, but thepresent invention can also be applied to a BGA type package in which asubstrate larger than the semiconductor chip is used in order to achievea higher pin count.

In FIG. 11 is shown a circuit board 1000 on which is mounted asemiconductor device 1100 fabricated by the method of the abovedescribed embodiment. The circuit board 1000 generally uses an organicsubstrate such as for example a glass epoxy substrate. On the circuitboard 1000, a wiring pattern of for example copper is formed as adesired circuit, and on the circuit board 1000 are provided solderballs. Then by mechanically connecting the solder balls of the wiringpattern and the external electrodes of the semiconductor device 1100, anelectrical connection between the two is achieved.

In this case, since the construction is such that strain caused in thesemiconductor device 1100 by differences in thermal expansion with thesurroundings and mechanical stress can be absorbed, even when thissemiconductor device 1100 is mounted on the circuit board 1000, both atthe time of connection and thereafter, the reliability can be improved.

It should be noted that the mounting area can be reduced to the mountingarea for bare chip mounting. For this reason, when this circuit board1000 is used in an electronic instrument, the electronic instrumentitself can be made more compact. Within the same area, a larger mountingarea is available, and higher functionality can also be achieved.

As an electronic instrument provided with this circuit board 1000, FIG.12 shows a notebook personal computer 1200.

It should be noted that, the present invention can be applied to varioussurface-mounted electronic components, whether active or passive.Electronic components include, for example, resistors, capacitors,coils, oscillators, filters, temperature sensors, thermistors,varistors, variable resistors, and fuses.

1. A substrate comprising: an insulating film in which a penetratinghole is formed, the penetrating hole extending between a first surfaceof the insulating film and a second surface of the insulating filmopposite to the first surface of the insulating film; a wiring patternthat is adhered to the first surface of the insulating film by anadhesive material, a first portion of the wiring pattern formed over thepenetrating hole, a part of the adhesive material formed on an internalwall surface forming the penetrating hole so as not to stop up thepenetrating hole; and an external electrode that contacts the firstportion of the wiring pattern and projecting through the penetratinghole and extending beyond the second surface of the insulating film. 2.The substrate as defined in claim 1, wherein a part of the adhesivematerial enters and exists within the penetrating hole.
 3. The substrateas defined in claim 1, wherein the adhesive material is an adhesivetape.
 4. The substrate as defined in claim 1, further comprising ananisotropic conductive material having conductive particles dispersed inan adhesive.
 5. The substrate as defined in claim 1, the externalelectrode being in contact with the part of the adhesive material. 6.The substrate as defined in claim 1, the external electrode being incontact with a first part of a surface of the part of the adhesivematerial, the first part of the surface of the part of the adhesivematerial facing a first opening of the penetrating hole in the secondsurface of the insulating film.
 7. A semiconductor device comprising: aninsulating film in which a penetrating hole is formed, the penetratinghole extending between a first surface of the insulating film and asecond surface of the insulating film opposite to the first surface ofthe insulating film; a wiring pattern that is adhered to the firstsurface of the insulating film by an adhesive material, a first portionof the wiring pattern formed over the penetrating hole, a part of theadhesive material formed on an internal wall surface forming thepenetrating hole so as not to stop up the penetrating hole; an externalelectrode that contacts the first portion of the wiring pattern andprojecting through the penetrating hole and extending beyond the secondsurface of the insulating film; and a semiconductor chip that has anelectrode electrically connected to the wiring pattern, thesemiconductor chip being mounted to the first surface of the insulatingfilm.
 8. The semiconductor device defined in claim 7, wherein a part ofthe adhesive material enters and exists within the penetrating hole. 9.The semiconductor device defined in claim 7, wherein the adhesivematerial is an adhesive tape.
 10. The semiconductor device defined inclaim 7, an outline form of the insulating film being larger than anoutline form of the semiconductor chip.
 11. The semiconductor devicedefined in claim 7, the external electrode being in contact with thepart of the adhesive material.
 12. The semiconductor device defined inclaim 7, the external electrode being in contact with a first part of asurface of the part of the adhesive material, the first part of thesurface of the part of the adhesive material facing a first opening ofthe penetrating hole in the second surface of the insulating film.